HOUSEFLIES ARE AN UNLIKELY RESERVOIR OR VECTOR FOR HELICOBACTER-PYLORI

The route of transmission of Helicobacter pylori from individual to in dividual remains undefined. It has recently been reported that the dom estic housefly, Musca domestica, when fed pure cultures of H. pylori, was able to harbor the organism in its midgut for up to 30 h (P. Grube l, S, Hoffman, F. K. Chong, N. A. Barstein, C. Mepani, and D. R, Cave, J. Clin. Microbiol. 35:1300-1303, 1997). Our investigation examined w hether houseflies could acquire H. pylori from fresh human feces. Dome stic houseflies (40 flies/group) were exposed for 24 h to feces from a n H. pylori-positive volunteer, feces from an H. pylori-negative volun teer, or feces from an H. pylori-negative volunteer to which a known a mount of viable H. pylori had been added. At various intervals, flies were sacrificed and the midguts were excised, homogenized, and plated in duplicate onto selective horse blood agar plates. All plates were i ncubated under microaerobic conditions at 37 degrees C for 14 days. Em ergent colonies presumptive of H. pylori were picked and tested bioche mically to confirm the identity as H. pylori. PI. pylori was not recov ered from houseflies fed human feces either naturally infected or arti ficially infected with H. pylori. These results suggest that the domes tic housefly is not a vector for transmission or a reservoir for H. py lori infection.